Kumiko Azetsu-Scott

Kumiko Azetsu-Scott
Fisheries and Oceans Canada | DFO

About

66
Publications
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Publications

Publications (66)
Technical Report
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We report on biogeochemical conditions of the Labrador Sea between 2014 and 2018 as measured during the Atlantic Zone Off-shelf Monitoring Program, which continue a time series that started in the late 90s.
Article
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Studies of marine microbioerosion in polar environments are scarce. They include our recent investigations of bioerosion traces preserved in sessile balanid skeletons from the Arctic Svalbard archipelago and the Antarctic Ross Sea. Here, we present results from a third study site, Frobisher Bay, in the eastern Canadian Arctic, together with a synth...
Article
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The Canadian Arctic is warming at three times the rate of the rest of the planet and the effects of climate change on the Arctic marine carbon cycle remains unconstrained. Baffin Bay is a semi-enclosed, Arctic basin that connects the Arctic Ocean to the north to the Labrador Sea to the south. While the physical oceanography of surface Baffin Bay is...
Article
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The goal of this paper is to give a detailed description of the coupled physicalbiogeochemical model of the Gulf of St. Lawrence that includes dissolved oxygen and carbonate system components, as well as a detailed analysis of the riverine contribution for different nitrogen and carbonate system components. A particular attention was paid to the re...
Article
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Bentho-pelagic life cycles are the dominant reproductive strategy in marine invertebrates, providing great dispersal ability, access to different resources, and the opportunity to settle in suitable habitats upon the trigger of environmental cues at key developmental moments. However, free-dispersing larvae can be highly sensitive to environmental...
Article
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Ocean acidification (OA) is increasing predictably in the global ocean as rising levels of atmospheric carbon dioxide lead to higher oceanic concentrations of inorganic carbon. The Gulf of Maine (GOM) is a seasonally varying region of confluence for many processes that further affect the carbonate system including freshwater influences and high pro...
Article
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Increasing atmospheric CO2, cold water temperatures, respiration, and freshwater inputs all contribute to enhanced acidification in Arctic waters. However, ecosystem effects of ocean acidification (derived from anthropogenic and/or natural sources) in the Arctic Ocean are highly uncertain. Zooplankton samples and oceanographic data were collected i...
Article
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Seawater total alkalinity (TA) is one important determinant used to monitor the ocean carbon cycle, whose spatial distributions have previously been characterized along the United States East Coast via discrete bottle samples. Using these data, several regional models for TA retrievals based on practical salinity (S) have been developed. Broad-scal...
Article
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The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2020 is an update of the previous version, GLODAPv2.2019...
Technical Report
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A regional climate model is used to make projections of future physical and biogeochemical conditions in the Gulf of St. Lawrence (GSL), Scotian Shelf, and Gulf of Maine. The regional climate model is forced with downscaled atmosphere from three Earth System Models (CanESM2, MPI-ESM-LR, and HadGEM-ES) using the Representative Concentration Pathway...
Preprint
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The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface to bottom ocean biogeochemical data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of water samples. GLODAPv2.2020 is an update of the previous version, GLODAPv2.2019. T...
Article
Full-text available
Syntheses of carbonate chemistry spatial patterns are important for predicting ocean acidification impacts, but are lacking in coastal oceans. Here, we show that along the North American Atlantic and Gulf coasts the meridional distributions of dissolved inorganic carbon (DIC) and carbonate mineral saturation state (Ω) are controlled by partial equi...
Technical Report
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Overview and synthesis of the present state of the Arctic Seas of Canada
Technical Report
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Specific case studies in support of the main technical report 3344
Article
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The Global Ocean Ship-Based Hydrographic Investigations Program (GO-SHIP) provides a globally coordinated network and oversight of 55 sustained decadal repeat hydrographic reference lines. GO-SHIP is part of the global ocean/climate observing systems (GOOS/GCOS) for study of physical oceanography, the ocean carbon, oxygen and nutrient cycles, and m...
Article
Full-text available
Ocean acidification (OA) describes the progressive decrease in the pH of seawater and other cascading chemical changes resulting from oceanic uptake of atmospheric carbon. These changes can have important implications for marine ecosystems, creating risk for commercial industries, subsistence communities, cultural practices, and recreation. Charact...
Chapter
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This chapter describes physical and chemical changes in the oceans surrounding Canada on decadal and longer time scales, and discusses these changes in the context of anthropogenic climate change and natural climate variability.
Article
Measurements of dissolved methane (CH 4 ) and carbonate system parameters were conducted in shelf and slope waters off Baffin Island and northern Labrador during September 2012 and August 2016 in order to investigate potential cold seeps and their influence on the marine carbonate system. Evidence of a strong near-bottom methane source was found at...
Article
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Northern oceans are in a state of rapid transition. Still, our knowledge of the likely effects of climate change and ocean acidification on key species in the food web, functionally important habitats and the structure of Arctic and sub-Arctic ecosystems is limited and based mainly on short-term laboratory studies on single species. This review dis...
Article
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Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on...
Article
Rapidly changing conditions in the Arctic can have a significant impact on biogeochemical cycles and can be particularly important in high latitude estuary-fjord systems with abundant and diverse freshwater sources. This study provides a first look into the inorganic carbon system and its relation to freshwater sources in Cumberland Sound in the ea...
Article
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Past trends and future projections of key atmospheric, oceanic, sea ice and biogeochemical variables were assessed to increase our understanding of climate change impacts on Canadian Arctic marine ecosystems. Four subbasins: Beaufort Sea, Canadian Arctic Archipelago, Baffin Bay/Davis Strait and Hudson Bay are evaluated. Limited observations, especi...
Article
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The Hudson Bay system (HBS) is a shallow inland sea in the Arctic, composed of Hudson Strait, Foxe Basin/Channel, James Bay and Hudson Bay. Dissolved inorganic carbon (DIC) and total alkalinity (TA) measurements were used to investigate the state of ocean acidification, specifically calcium carbonate saturation states (Ω) and pH. The freshwater sou...
Article
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We present observation based estimates of the transport of dissolved inorganic carbon (DIC) across the four main Arctic Ocean gateways (Davis Strait, Fram Strait, Barents Sea Opening and Bering Strait). Combining a recently derived velocity field at these boundaries with measurements of DIC, we calculated a net summertime pan-Arctic export of 231±4...
Article
Depth profiles of dissolved methane were measured along three transects of Davis Strait and the northern Labrador Sea in October 2011. Concentrations ranged from 0.2 nmol L- 1 (6 % saturation) in the remarkably methane depleted Baffin Bay Deep Water to 38.8 nmol L- 1 (1057 % saturation) in localised subsurface anomalies near the Baffin Island Shelf...
Article
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Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has lim...
Technical Report
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Within the Aquatic Climate Change Adaptation Services Program (ACCASP), past trends and future projections of key climatic variables such as air and water temperature, precipitation, winds and storms, sea ice and biogeochemical variables are assessed. The assessment forms the basis for the impact, vulnerabilities, and opportunities analysis needed...
Article
study provides the first physically based mass-balanced transport estimates of dissolved inorganic nutrients (nitrate, phosphate, and silicate) for the Arctic Ocean. Using an inverse model-generated velocity field in combination with a quasi-synoptic assemblage of hydrographic and hydrochemical data, we quantify nutrient transports across the main...
Article
Freshwater transport through Davis Strait can supply additional buoyancy to the deep convection region of the Labrador Sea which influences the strength of the meridional overturning circulation and consequently the global climate. The freshwater contribution from local sea ice meltwater, meteoric water (fluvial, glaciofluvial and precipitation) an...
Article
Distributions of sea-ice melt (SIM) and runoff (RW) were determined in Hudson Bay (Canada) using salinity and oxygen isotope (δ18O) tracers. In late summer/early fall, stations throughout the Bay exhibited a summer surface mixed layer (SSML) 30–60m deep, which contained the seasonal freshwater inputs. The SSML overlies a cold subsurface water, exte...
Article
The seasonal variability of inorganic carbon in the surface waters of the Scotian Shelf region of the Canadian northwestern Atlantic Ocean is investigated. Seasonal variability is assessed using hourly measurements covering a full annual cycle of the partial pressure of CO2, (pCO2), and hydrographic variables obtained by an autonomous moored instru...
Article
The coastal oceans have relatively large fluxes of CO2, but the temporal variability of these systems is high. Compared to open ocean systems, the variability of the CO2 system in coastal regions remains poorly understood. The Scotian Shelf is a highly productive area of the Canadian northwestern Atlantic Ocean. The region is host to active fisheri...
Article
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Ocean acidification is predicted to occur first in polar oceans. We investigated the saturation state of waters with respect to calcite (Wcal) and aragonite (Warg) in six sections along an Arctic outflow pathway through the Canadian Arctic Archipelago (CAA) and into the northwestern Atlantic using dissolved inorganic carbon and total alkalinity mea...
Article
Davis Strait is a critical site for investigating freshwater exchange between the Arctic and North Atlantic Oceans and an ideal location for monitoring temporal and spatial variability of the critical upstream boundary condition for Labrador Sea convection. Fluxes through the Strait represent the net integrated Canadian Archipelago throughflow, ove...
Article
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The freshwater composition of waters on the southeast Greenland shelf and slope are described using a set of high-resolution transects occupied in summer 2004, which included hydrographic, velocity, nutrient, and chemical tracer measurements. The nutrient and tracer data are used to quantify the fractions of Pacific Water, sea ice melt, and meteori...
Article
Many studies have been carried out around the world to understand what happens to carbon dioxide (CO2) once it is emitted into the atmosphere, and how it relates to long-term climate change. However, the sea surface pCO2 observations on volunteer observation ships and research vessels concentrated in the North Atlantic and North Pacific. To assess...
Article
Many observations to clarify the fate of CO2 in the atmosphere, related with long term climate change, have been carried out in the world. However, the sea surface pCO2 observations on volunteer observation ships and research vessels concentrated in the North Atlantic and North Pacific. To assess the spatial and temporal variations of surface pCO2...
Chapter
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Warming of Earth's climate system is now unequivocal and most of the observed warming since the mid-20 th century is very likely due to increasing greenhouse gas concentrations in the atmosphere. This is the conclusion of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) released in 2007. Observations show increas...
Article
Produced water undergoes changes in its physical chemistry including precipitation of heavy metals after being discharged and mixed with ambient seawater. Potential impacts of the precipitation of heavy metals on their transport and toxicity were studied using samples from offshore oil production sites on the Scotian Shelf off eastern Canada. Conce...
Article
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A three-dimensional ocean circulation model is used to examine the uptake, spreading and interannual variability of chlorofluorocarbons (CFCs) in the North Atlantic Ocean during the 50-year period from 1948 to 1997. The model is forced by climatological and North Atlantic Oscillation (NAO) related monthly mean surface forcing, and a realistic, time...
Article
The role of transparent exopolymer particles (TEP) in the biogeochemical cycle of reactive elements in the upper ocean was studied using a thorium isotope (234Th) as a tracer during a spring bloom in a coastal bay. TEP concentrations were consistently higher at 0 m during the bloom than at 5 m, where chlorophyll-a concentrations were highest, even...
Article
An extensive study of halocarbon tracers, chlorofluorocarbons (CFCs) and carbon tetrachloride (CCl4), based on over 100 stations in the Labrador Sea, demonstrated water mass structure and ventilation processes. Regional convection and isopycnal mixing of four water masses including newly ventilated Labrador Sea Water (LSWshallow), Labrador Sea Wate...
Chapter
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It has been suggested that the deep-sea gorgonian coral Primnoa resedaeformis may be an important paleoceanographic archive. Seventeen colonies collected from the upper slope of the NW Atlantic margin (229 – 447 m) were analyzed to see if skeletal Mg/Ca is related to temperature. Analyses were focused on the calcite cortex region of skeletal sectio...
Chapter
Full-text available
Offshore oil and gas drilling operations take place in some of the world's most biologically productive oceanic waters. An ongoing concern related to the development of this industry is that exposure to contaminants from waste discharges may cause ill effects on organisms and their habitat. Environmental Effects Monitoring (EEM) programs are undert...
Article
Deep convection in the Labrador Sea ventilates the water column every winter. Depths of deep convection are influenced by the North Atlantic Oscillation (NAO). During the NAO positive phase, convection reaches over 2000m as observed in early 1990's, while during the NAO negative phase, convection becomes shallower to 500-1000m. Convection regimes i...
Article
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1] A model of the North Atlantic Ocean is used to simulate the spreading of CFC-12 from the Labrador Sea deep convection site. The standard version of the model fails to capture the local maximum in CFC-12 concentration that is observed along the continental slope of the western boundary. Hydrographic data are used to apply a simple correction to t...
Article
The high abundance of transparent exopolymer particles (TEP) in marine and freshwater greatly affects particle dynamics. TEP act as glue for colliding particles and form the matrix in aggregates, thereby altering aggregation dynamics. We studied the sinking behavior of freshly produced, particle-free TEP and of aggregates composed of TEP and latex...
Article
Annual measurements of concentrations of chlorofluorocarbons (CFCs) along the Labrador Sea WOCE repeat section (AR7W) during 1991-2000 revealed increasing CFC-12 concentrations in the surface layer (<100 m), the newly ventilated Labrador Seawater (LSW), North East Atlantic Deep Water (NEADW), and Denmark Strait Overflow Water (DSOW). In newly venti...
Article
Full-text available
A detailed study of distribution of suspended sediments in an East Greenland fjord with a high iceberg production rate reveals the existence of intermediate nepheloid layers (INLs). Observed INLs extended from the head to the mouth of the fjord at water depths between 100 and 400 m. Particulate organic carbon and nitrogen, chlorophyll a, and nutrie...
Article
A detailed study of the oxygen isotope composition ([delta]18O) was carried out along a transect between Iceland and East Greenland, which includes the West Iceland Shelf, Denmark Strait, the Kangerdlugssuaq Trough on the East Greenland Shelf and the Kangerdlugssuaq Fjord. Vertical profiles of the oxygen isotope composition in a fjord with tidewate...
Article
A new method to measure adhesion force, or that force that holds surfaces in molecular contact, is used to quantify the effect of natural surface films on adhesion between surfaces immersed in seawater. Results of measurements demonstrate that bacterial films significantly modify surface adhesion and that the resulting interfacial force is nearly i...
Article
Intermittent, intermediate nepheloid layers were observed on the Scotian Shelf in late April, 1987. These 10–30 m thick nepheloid layers were found between 140 and 200 m in the main part of Emerald Basin and 120–140 m in the northern basin, well below the surface mixed layer and about 90 m above the sea bed in both cases. Both biological and physic...
Article
Bottom nepheloid layer formation was observed through a time series study of the vertical distribution of suspended particles conducted during and after a phytoplankton bloom in a small coastal basin, Bedford Basin, Nova Scotia, Canada. In this study, we measured the suspended particle distribution over a 6 month period using a backward-recording (...